What Causes Burning Sensation When Clothing Touches The Mole Below The Breast?

I have a "mole" on my lower chest, just below my breast. I have had it all of my life. It is raised and my husband and I have always referred to it as my third nipple (to give you an idea of what it looks like). Anyway, just yesterday this "mole" started hurting if my clothing touches it. It almost burns. I plan to see my doctor if it is something that you cannot explain away as normal.